距今 literally means 'distance from now' and functions as a time expression indicating how many years (or other time units) have passed since a past event up to the present moment. The character 距 means 'to be distant from' or 'separation', while 今 means 'now' or 'the present'. Together, they form a fixed phrase used almost exclusively in historical, archaeological, or academic contexts to quantify temporal distance — for example, when dating ancient artifacts, fossils, or historical events.

This phrase always appears before a time quantity (e.g., 五千年前, 三百年) and is followed by a noun or verb phrase describing the event or object being dated. It carries a formal, objective tone and is rarely used in casual speech. You’ll commonly see it in textbooks, museum labels, news reports about discoveries, or scholarly writing — never in daily conversation like 'I ate lunch two hours ago' (which uses 过去 instead).